Laminated film for forming an easily openable tightly sealed bag

Abstract

A laminate film for forming a tightly sealed bag that can be opened easily by tearing at an edge thereof. The film is a laminate of a substrate layer and a heat seal layer, the substrate layer having a multiplicity of through cuts formed therein, said through cuts being partially or wholly filled by the heat seal layer material.

What is claimed is: 
     
       1. A laminated film for forming an easily openable tightly sealed bag comprising at least a substrate layer and heat seal layer, wherein the tensile strength of the heat seal layer is smaller than that of the substrate layer and the tear strength of the heat seal layer is greater than that of the substrate layer and wherein said substrate layer has a multiplicity of through cuts formed therein at least substantially in the edges, said through cuts being at least partially filled with the material of said heat seal layer. 
     
     
       2. The laminate film of claim 14 wherein said heat seal layer material at least partially penetrates into said through cuts and at least partially closes said through cuts. 
     
     
       3. The film of claim 1 wherein the substrate layer is selected from the group consisting of polyamide, polyester, polypropylene, cellophane, cellulose acetate and rigid polyvinyl chloride and the heat seal layer is selected from the group consisting of low-density polyethylene, non-stretched polypropylene, and polyethylene-vinyl acetate copolymer. 
     
     
       4. The film of claim 1 wherein the ratio of thickness of the substrate layer to the thickness of the heat seal layer is in the range of 5:1 to 1:10. 
     
     
       5. The film of claim 1, wherein the thickness of the substrate layer is 10 to 50 μm. 
     
     
       6. The film of claim 1, wherein the thickness of the heat seal layer is 10 to 100 μm. 
     
     
       7. The film of claim 5, wherein the thickness of the heat seal layer is 10 to 100 μm. 
     
     
       8. The film of claim 1 having a total thickness of 20 to 150 μm. 
     
     
       9. The film of claim 1 wherein the tensile strength of the heat seal layer is not more than 2/3 and not less than 1/20 the tensile strength of the substrate layer and wherein the tear strength of the heat seal layer is not less than 5 times and not more than 150 times greater than the tear strength of the substrate layer. 
     
     
       10. The film of claim 14 wherein the material of said heat seal layer wholly fills said through cuts.